Model NM-21FFT radio noise meter is designed specifically for use by the power industry to make highly accurate measurements of broadcase band EMI pollution. The NM-21FFT operates at one fixed frequency and is available with a standard frequency of either 834 kHz or 1000 kHz. It is also available on special order with a fixed frequency anywhere in the range of 600 1500 kHz. Due to the single frequency capability, the instrument is inherently high in senstivity and simple to operate. The absence of broad frequency coverage eliminates all tuning and calibration requirements. It also enables the circuitry to be designed for high image rejection, high IF rejection, low spurious response and high overall accuracy. The NM-21FFT conforms with NEMA-107 and ASA C63.2 specifications for single frequency RFI instruments and is compatible with the NM-17/27A and NM-25T for all pulse repetition rates above 50 pulses per second. The instrument is hand portable, withstands rough field use and has low (5 watt) power consumption.
